Method of making a nozzle

ABSTRACT

Methods of making nozzles are disclosed. More specifically, methods of making nozzles that may be used as components of a fuel injection system are disclosed.

FIELD

The present description relates to methods of making nozzles.Specifically, the present description relates to methods of makingnozzles that may be used as components of a fuel injection system.

SUMMARY OF THE INVENTION

In one aspect, the present description relates to a method offabricating a nozzle. The method involves a number of steps, including afirst step of casting and curing a first material in order to form afirst microstructured pattern in the first material. The firstmicrostructured pattern includes a plurality of discretemicrostructures. The casting and curing step may involve casting a firstmaterial in a first cast, curing the first material, and removing thematerial from the first cast. The method further involves replicatingthe first microstructured pattern in a second material different thanthe first material to make a replicated structure. Next, the secondmaterial of the replicated structure is planarized to expose tops of themicrostructures in the plurality of microstructures in the firstmicrostructured pattern. The method then includes removing the firstmaterial resulting in a nozzle having a plurality of holes in the secondmaterial and corresponding to the plurality of microstructures in thefirst microstructured pattern.

In another aspect, the present description relates to another method offabricating a nozzle. The method includes the first step of extruding afirst material in order to form a first microstructured pattern in thefirst material. The first microstructured pattern includes a pluralityof discrete microstructures. The method further involves replicating thefirst microstructured pattern in a second material different than thefirst material to make a replicated structure. Next, the second materialof the replicated structure is planarized to expose tops of themicrostructures in the plurality of microstructures in the firstmicrostructured pattern. The method then includes removing the firstmaterial resulting in a nozzle having a plurality of holes in the secondmaterial and corresponding to the plurality of microstructures in thefirst microstructured pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1E combine to create a flow chart of a method of fabricating anozzle according to the present description.

FIGS. 2A-2B illustrate an initial cast and cure step.

FIG. 3 is a diagram of an apparatus used to produce a microstructuredfilm by extrusion.

FIG. 4 is a schematic three-dimensional view of a microstructure.

FIG. 5 is a schematic three-dimensional view of a microstructure.

FIG. 6 is a perspective view of a film with a plurality ofmicrostructures.

FIG. 7 is a backlit photomicrograph of a fuel injector nozzle producedaccording to Example 1.

FIG. 8 is a backlit photomicrograph of a fuel injector nozzle producedaccording to Example 2.

FIG. 9 is a photomicrograph of an array of microstructures according toExample 3.

DETAILED DESCRIPTION

Fuel injection is increasingly becoming the preferred method for mixingfuel and air in internal combustion engines, as fuel injection generallycan be used to increase fuel efficiency of the engine and reduceshazardous emissions. Fuel injectors generally include a nozzle with aplurality of nozzle through-holes for atomizing the fuel under pressurefor combustion. Increasingly stringent environmental standards requiremore efficient fuel injectors. The search for more efficient fuelinjectors has led to investigation of a number of varying sizes andshapes of fuel injector nozzles, such as those described in commonlyowned and assigned PCT Publ. No. WO 2011/014607, the entirety of whichis incorporated by reference herein in its entirety. In addition to thesearch for optimally sized and shaped fuel injector nozzles, has comethe search for new methods of creating highly effective nozzles. Onesuch method begins with structurization using a use of two-photonprocess described in PCT Publ. No. WO 2011/014607, described above. Thepresent description relates to other new and effective methods ofproviding nozzles for use in high efficiency fuel injectors.

The term “nozzle” will be used throughout this description. It should beunderstood that the term “nozzle” may have a number of differentmeanings in the art. In some specific references, the term nozzle has abroad definition. For example, U.S. Patent Publication No. 2009/0308953A1 (Palestrant et al.), discloses an “atomizing nozzle” which includes anumber of elements, including an occluder chamber 50. This differs fromthe understanding and definition of nozzle put forth herewith. Forexample, the nozzle of the current description would correspondgenerally to the orifice insert 24 of Palestrant et al. In general, thenozzle of the current description can be understood as the final taperedportion of an atomizing spray system from which the spray is ultimatelyemitted, see e.g., Merriam Webster's dictionary definition of nozzle (“ashort tube with a taper or constriction used (as on a hose) to speed upor direct a flow of fluid.” Further understanding may be gained byreference to U.S. Pat. No. 5,716,009 (Ogihara et al.) issued toNippondenso Co., Ltd. (Kariya, Japan). In this reference, again, fluidinjection “nozzle” is defined broadly as the multi-piece valve element10 (“fuel injection valve 10 acting as fluid injection nozzle . . .”—see col. 4, lines 26-27 of Ogihara et al.). The current definition andunderstanding of the term “nozzle” as used herein would relate to firstand second orifice plates 130 and 132 and potentially sleeve 138 (seeFIGS. 14 and 15 of Ogihara et al.), for example, which are locatedimmediately proximate the fuel spray. A similar understanding of theterm “nozzle” to that described herein is used in U.S. Pat. No.5,127,156 (Yokoyama et al.) to Hitachi, Ltd. (Ibaraki, Japan). There,the nozzle 10 is defined separately from elements of the attached andintegrated structure, such as “swirler” 12 (see FIG. 1(II)). Theabove-defined understanding should be understood when the term “nozzle”is referred to throughout the remainder of the description and claims.

FIGS. 1A-1E provide a flow chart of one embodiment of a method forfabricating a nozzle according to the present description. FIG. 1Aillustrates providing a first microstructured pattern 110 in a firstmaterial 102. The first microstructured pattern 110 includes a pluralityof discrete microstructures 104. Discrete microstructures have a heightt₁. In this first embodiment the first microstructured pattern is formedby a cast and cure process. A simplified diagram of one such process isillustrated in FIG. 2A. A cast 200 with a negative of microstructurepattern 110 is provided. A given volume of curable material, in manycases a polymer, is cast into cast 200. In some cases, the polymer maybe a silicone, acrylic, rubber, or fluoropolymer. Once the first uncuredmaterial 100 has been cast into cast 200, it is cured by an appropriatemethod. For example, in some embodiments, the first material 100 may becured by thermal curing, or potentially exposure to UV radiation. Otherappropriate curing methods known in the art, such as applying otherforms of radiation, may also be used. Once curing has occurred, thefirst microstructured material 102 may then be removed from mold 200 asshown in FIG. 2B. First microstructured material 102 will containmicrostructures 104 arranged in a first microstructured pattern 110.Typically, the mold and the cured first microstructured material areseparated physically (i.e., by carefully pulling them apart withoutdamaging the mold and/or the cured first microstructured material).Separation may be accomplished manually or via the use of suitable toolssuch as tweezers etc. The result of these steps may provide for themicrostructured material 102 of FIG. 1A.

In another embodiment, the first material 102 of FIG. 1A having firstmicrostructured pattern 110, may be created by an extrusion process. Aclose up view of exactly how the extrusion process may operate isillustrated in FIG. 3. A film may be cast between a pair of rollers thatare spaced apart by a specific dimension, as is illustrated in FIG. 3,where a film 302 is pulled from a reservoir 301, through a die 300 by anextrusion roller 304. The film 302 is nipped between the extrusionroller 304 and a second roller 306. Where the film 302 has a surfacestructure, the second roller 306 may be a pattern roller, provided witha prescribed surface for embossing a pattern onto the film 302. Forexample, where the film 302 is being manufactured as a prismatic film,the second roller 306 is provided with a plurality of prismaticstructures 308 around its surface, which create complementaryimpressions in the upper surface 312 of the film 302. The pattern rollermay have a diameter whose value lies in the range 15 cm-60 cm. Theextrusion roller 304 may also be provided with an embossing pattern thatis used to emboss a pattern onto the lower surface 318 of the film.After passing between the rollers 304 and 306, the film 302 cools, forexample in a cooler 320, and maintains the patterns embossed on it bythe rollers 304 and 306. In the particular embodiment shown, theextrusion roller 304 has a surface 316 that has random variations inheight on the lower surface of the film 318.

The upper roller 306 may be provided with many different types ofembossing patterns. Examples of embossing patterns that may be used onthe upper roller 306 include a prismatic pattern that may correspond to,e.g., a brightness enhancement film, a lenticular pattern for alenticular film, a hemispheric pattern, and the like. In addition, theprismatic structures on the upper roller 306 may be arranged in adirection perpendicular to the direction of rotation, around thecircumference of the roller 306, rather than in a direction parallel tothe direction of rotation, as shown in FIG. 3. The upper roller 306 mayalso be smooth to provide a flat film surface, or may be provided with asurface for embossing a pattern on the upper surface 312 of the film302. The surface of the extrusion roller 304 may potentially include anirregular embossing pattern. After forming the plurality ofmicrostructures on surface 312, the sheet may be cut into moremanageable sized pieces and may serve as the first material 102 havingfirst microstructured pattern 110 in FIG. 1A.

Besides prismatic or hemispheric shaped microstructures, a number ofother commercially available products with varying microstructurepatterns and shapes may be appropriate. For example, the discretemicrostructures 104 may be shaped such as re-closeable fasteners withposts or mushroom-shaped tops. These structures may be made by theprocesses shown in commonly owned and assigned U.S. Pat. Nos. 5,845,375and 6,132,660, which are incorporated by reference herein.

Other approaches may be utilized to produce a film having one or morestructured surfaces, including embossing a sheet, injection molding andcompression molding. In one particular approach, a film of embossablematerial, applied to a web, is compressively held against a patternsurface to emboss the complement of the pattern surface onto the film.The embossable material may be a thermoplastic material, such aspoly(ethylene teraphthlate), polaymides such as nylon,poly(styrene-acrylonitrile), poly(acrylonitrile-butadiene-styrene),polyolefins such as polypropylene, and plasticized polyvinyl alcohol. Insuch embodiments, the film may be cooled while being held against thepatterned surface in order to solidify the material with the patternembossed thereon. In a variation of this approach, the embossablematerial may be a curable polymer that is cured, or partially curedbefore the patterned surface is removed.

As mentioned above, the first material 102 of FIG. 1A may be anappropriate polymer, such as a silicone, acrylic, rubber orfluoropolymer. In another sense, the first material 102 may beunderstood as a hardcoat composition formed from the reaction product ofa polymerizable composition. As such, at times throughout thisdescription, the first material may be described as a “hardcoat.”Specifically, the first material 102 may be a hardcoat compositionformed from the reaction product of a polymerizable compositioncomprising one or more urethane (meth)acrylate oligomer(s). Typically,the urethane (meth)acrylate oligomer is a di(meth)acrylate. The term“(meth)acrylate” is used to designate esters of acrylic and methacrylicacids, and “di(meth)acrylate” designates a molecule containing two(meth)acrylate groups.

Oligomeric urethane (meth)acrylates may be obtained commercially; e.g.,from Sartomer under the trade designation “CN 900 Series”, such as“CN981” and “CN981B88. Oligomeric urethane (meth)acrylates are alsoavailable from Cytec Industries Inc. (Woodland Park, N.J.) and Cognis(Monheim am Rhein, Germany). Oligomeric urethane (meth)acrylates mayalso be prepared by the initial reaction of an alkylene or aromaticdiisocyanate of the formula OCN—R³—NCO with a polyol. Most often, thepolyol is a diol of the formula HO—R⁴—OH, wherein R³ is a C₂₋₁₀₀alkylene or an arylene group and R⁴ is a C₂₋₁₀₀ alkylene or alkoxygroup. The intermediate product is then a urethane diol diisocyanate,which subsequently can undergo reaction with a hydroxyalkyl(meth)acrylate. Suitable diisocyanates include alkylene diisocyanatessuch as 2,2,4-trimethylhexylene diisocyanate. The urethane(meth)acrylate oligomer employed herein is preferably aliphatic.

The urethane (meth)acrylate oligomer contributes to the conformabilityand flexibility of the cured hardcoat composition. In preferredembodiments, a 5 micron thick film of the cured hardcoat composition issufficiently flexible such that it can be bent around a 2 mm mandrelwithout cracking.

In addition to being flexible, the hardcoat has good durability andabrasion resistance. For example, a 250 micrometer (5 mil) thick film ofthe cured hardcoat exhibits a change in haze of less than 10% aftercommonly used oscillating sand abrasion testing.

The kind and amount of urethane (meth)acrylate oligomer is selected inorder to obtain a synergistic balance of flexibility and good abrasionresistance.

One suitable urethane (meth)acrylate oligomer that can be employed inthe hardcoat composition is available from Sartomer Company (Exton, Pa.)under the trade designation “CN981B88”. This particular material is analiphatic urethane (meth)acrylate oligomer available under the tradedesignation CN981 blended with SR238 (1,6 hexanediol diacrylate). Othersuitable urethane (meth)acrylate oligomers are available from SartomerCompany under the trade designations “CN9001” and “CN991”. The physicalproperties of these aliphatic urethane (meth)acrylate oligomers, asreported by the supplier, are set forth in Table 1 as follows:

TABLE 1 Physical Properties of Aliphatic Urethane Meth(Acrylate)Oligomers Tensile Tg (° C.) as Trade Viscosity Strength Elongationdetermined by Designation Cps at 60° C. (MPa) (%) DSC CN981 6190 7.67 8122 CN981B88 1520 10.48 41 28 CN9001 46,500 22.72 143 60 CN991 660 37.0879 27

The reported tensile strength, elongation, and glass transitiontemperature (Tg) properties are based on a homopolymer prepared fromsuch urethane (meth)acrylate oligomer. These embodied urethane(meth)acrylate oligomers can be characterized as having an elongation ofat least 20% and typically no greater than 200%; a Tg ranging from about0 to 70° C.; and a tensile strength of at least 6.89 MPa (1,000 psi), orat least 34.48 MPa (5,000 psi).

These embodied urethane (meth)acrylate oligomers and other urethane(meth)acrylate oligomers having similar physical properties that canusefully be employed at concentrations ranging from at least 25 wt-%, 26wt-%, 27 wt-%, 28 wt-%, 29 wt-%, or 30 wt-% based on wt-% solids of thehardcoat composition. When the hardcoat composition further includesinorganic nanoparticles such as silica, the total concentration of theurethane (meth)acrylate oligomer is typically higher, ranging from about40 wt-% to about 75 wt-%. The concentration of urethane (meth)acrylateoligomer can be adjusted based on the physical properties of theurethane (meth)acrylate oligomer selected.

The urethane (meth)acrylate oligomer is combined with at least onemulti(meth)acrylate monomer comprising three or four (meth)acrylategroups. The multi(meth)acrylate monomer increases the crosslinkingdensity and thereby predominantly contributes the durability andabrasion resistance to the cured hardcoat.

Suitable tri(meth)acryl containing compounds include glyceroltriacrylate, trimethylolpropane triacrylate, ethoxylated triacrylates(for example, ethoxylated (3) trimethylolpropane triacrylate,ethoxylated (6) trimethylolpropane triacrylate, ethoxylated (9)trimethylolpropane triacrylate, ethoxylated (20) trimethylolpropanetriacrylate), pentaerythritol triacrylate, propoxylated triacrylates(for example, propoxylated (3) glyceryl triacrylate, propoxylated (5.5)glyceryl triacrylate, propoxylated (3) trimethylolpropane triacrylate,propoxylated (6) trimethylolpropane triacrylate), trimethylolpropanetriacrylate, pentaerythritol triacrylate, andtris(2-hydroxyethyl)isocyanurate triacrylate.

Higher functionality (meth)acryl containing compounds includeditrimethylolpropane tetraacrylate, ethoxylated (4) pentaerythritoltetraacrylate, and pentaerythritol tetraacrylate.

Commercially available cross-linkable acrylate monomers include thoseavailable from Sartomer Company (Exton, Pa.) such as trimethylolpropanetriacrylate available under the trade designation SR351, pentaerythritoltriacrylate available under the trade designation SR444,dipentaerythritol triacrylate available under the trade designationSR399LV, ethoxylated (3) trimethylolpropane triacrylate available underthe trade designation SR454, ethoxylated (4) pentaerythritoltriacrylate, available under the trade designation SR494, andtris(2-hydroxyethyl)isocyanurate triacrylate, available under the tradedesignation SR368.

The hardcoat may additionally comprise one or more di(meth)acrylcontaining compounds. For example, the urethane (meth)acrylate oligomermay be purchased preblended with a di(meth)acrylate monomer such as inthe case of CN988B88. Suitable monomers include, for example,1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate,1,6-hexanediol diacrylate, 1,6-hexanediol monoacrylate monomethacrylate,ethylene glycol diacrylate, alkoxylated aliphatic diacrylate,alkoxylated cyclohexane dimethanol diacrylate, alkoxylated hexanedioldiacrylate, alkoxylated neopentyl glycol diacrylate, caprolactonemodified neopentylglycol hydroxypivalate diacrylate, caprolactonemodified neopentylglycol hydroxypivalate diacrylate,cyclohexanedimethanol diacrylate, diethylene glycol diacrylate,dipropylene glycol diacrylate, ethoxylated (10) bisphenol A diacrylate,ethoxylated (3) bisphenol A diacrylate, ethoxylated (30) bisphenol Adiacrylate, ethoxylated (4) bisphenol A diacrylate, hydroxypivalaldehydemodified trimethylolpropane diacrylate, neopentyl glycol diacrylate,polyethylene glycol (200) diacrylate, polyethylene glycol (400)diacrylate, polyethylene glycol (600) diacrylate, propoxylated neopentylglycol diacrylate, tetraethylene glycol diacrylate,tricyclodecanedimethanol diacrylate, triethylene glycol diacrylate, andtripropylene glycol diacrylate.

Returning to FIG. 1A, once the first microstructured pattern has beenformed in first material 102 by either cast and cure method of FIGS.2A-B or the extrusion method shown in FIG. 3 using the materialsdiscussed above, the first microstructured pattern 110 is replicated.Looking at FIG. 1B, first, an optional seed layer 106 may be applied onthe microstructured surface. The top surface 108 of first material 102is metalized or made electrically conductive by coating the top surfacewith a thin electrically conductive seed layer 106 similar to seedlayer.

Conductive seed layer 106 can include any electrically conductivematerial that is desirable in an application. Exemplary conductivematerials include silver, chromium, gold and titanium as well asconductive polymers such as polyacetylene, polyphenylene vinylene, polyaniline, polythiphene and the like. In some cases, seed layer 106 has athickness that is less than about 100 nm, less than about 50 nm, or lessthan about 40 nm, or less than about 30 nm, or less than about 20 nm.

Next, as schematically illustrated in FIG. 1C, seed layer 106 is used toelectroplate first microstructured pattern with a second materialdifferent than the first material resulting in a layer 120 of the secondmaterial. In some cases, the electroplating of first microstructuredpattern 110 is continued until the minimum thickness t₂ of layer 120 isgreater than t₁, the height of the microstructures 104 and, thereby,form blind holes in the layer 120 with the microstructures 104. In somecases, height t₂ is substantially equal to height t₁. Suitable secondmaterials for electroplating include silver, passivated silver, gold,rhodium, aluminum, enhanced reflectivity aluminum, copper, indium,nickel, chromium, tin, and alloys thereof. In other embodiments, thesecond material may be a ceramic that is deposited on firstmicrostructured pattern. Such a ceramic material may be formed, e.g., bya sol-gel process as described in commonly owned and assigned U.S. Pat.No. 5,453,104, or by photocuring of a ceramic-filled or pre-ceramicpolymeric composition as described in commonly owned and assigned U.S.Pat. Nos. 6,572,693, 6,387,981, 6,899,948, 7,393,882, 7,297,374, and7,582,685, each of which is herein incorporated by reference in itsentirety. Such ceramic materials may comprise, e.g., silica, zirconia,alumina, titania, or oxides of yttrium, strontium, barium, hafnium,niobium, tantalum, tungsten, bismuth, molybdenum, tin, zinc, lanthanideelements (i.e. elements having atomic numbers ranging from 57 to 71,inclusive), cerium and combinations thereof.

Next, top surface of 122 of layer 120 is ground until tops 112 ofmicrostructures 104 are exposed. The grinding or polishing can beaccomplished using any grinding method that may be desirable in anapplication. Exemplary grinding methods include surface grinding andmechanical milling. In some cases, the first material is softer than thesecond material. For example, in some cases, the first material ispolycarbonate and the second material is a nickel alloy. In such cases,small portions of tops 112 can be removed during the grinding process toensure that the tops of all the microstructures in first microstructuredpattern 110 are exposed. In such cases, the grinding results, asschematically illustrated in FIG. 1D, in a layer 124 of the secondmaterial planarizing the first microstructured pattern and exposing tops112 of the microstructures in the plurality of microstructures in thefirst microstructured pattern. Layer 124 of the second material has atop surface 126 that is substantially even with tops 112 ofmicrostructures 104. The microstructures have a height t₃ that can beslightly less than t₁.

Although in FIGS. 1A-1D, the microstructures 104 are illustrated ashaving flattened tops initially, this need not be the case. In a numberof embodiments the microstructures in the initial step may have a peakedsurface. This may be especially appropriate as this portion of themicrostructure may act as a sacrificial portion that aids in providingoptimal planarization during the grinding step. A better understandingof this concept may be understood by reference to commonly owned andassigned U.S. patent Ser. No. 10/054,094, incorporated herein byreference in its entirety.

Next, as illustrated in FIG. 1E, first material 104 is removed,resulting in a layer 130 of the second material that includes aplurality of through-holes 132 that correspond to the plurality ofmicrostructures in first microstructured pattern 110. Holes 130 includehole entries 136 and hole exits 134. The layer 130 made up of secondmaterial and may be any of the appropriate metals mentioned above, e.g.nickel, or may be, for example, ceramic. Optionally, the individualmicrostructures, each bearing a hole entry 136 and hole exit 134 may besingulated by dividing them from one another along, e.g., lines 138. Theindividual microstructures may then potentially be recombined in adesired pattern by an appropriate means, such as laser welding. In otherembodiments, the microstructured pattern will be cast and cured or gothrough the extrusion process such that the final pattern matches thatof the first material's first microstructured pattern.

Typically, the first material and the second material that includesplurality of holes are separated physically (i.e., by carefully pullingthem apart without damaging the mold and/or the cured firstmicrostructured material. Separation may be accomplished manually or viathe use of suitable tools such as tweezers etc. It is also possible toremove the first material chemically, for example, by dissolving thefirst material in a suitable solvent such as acetone, ethyl alcohol,isopropyl alcohol or the like. Alternately one may use an etchant suchas an aqueous solution of KOH. The first material and the secondmaterial may also be separated thermally by melting or burning of thefirst material at a suitable temperature without deforming, melting orotherwise damaging the second material.

In some cases, the plurality of discrete microstructures formed includesa discrete microstructure that is a three-dimensional rectilinear body,a portion of a three-dimensional rectilinear body, a three-dimensionalcurvilinear body, a portion of a three-dimensional curvilinear body, apolyhedron, a cone, or a tapered microstructure.

In some cases, a disclosed microstructure can be a three-dimensionalrectilinear body such as a polyhedron, such as a tetrahedron or ahexahedron, a prism, or a pyramid, or a portion, or a combination, ofsuch bodies, such as a frustum. For example, FIG. 4 is a schematicthree-dimensional view of a microstructure 420 that is disposed on asubstrate 410 and includes a planar or flat base 430, a planar or flattop 440 and a side 450 that connects the top to the base. Side 450includes a plurality of planar or flat facets, such as facets 460, 465and 470. Microstructure 420 can be used as a mold to fabricate holes foruse in, for example, a nozzle.

In some cases, a disclosed microstructure can be a three-dimensionalcurvilinear body or a portion of such body, such as a segment of asphere, an asphere, an ellipsoid, a spheroid, a paraboloid, a cone or atruncated cone, or a cylinder. For example, FIG. 5 is a schematicthree-dimensional view of a microstructure 520 that is disposed on asubstrate 510 and includes a planar or flat base 530, a planar or flattop 540 and a curvilinear side 550 that connects the top to the base. Inthe exemplary microstructure 520, top 540 and base 530 have the sameshape. Microstructure 520 tapers narrower from base 530 to top 540. As aresult, top 540 has a smaller area than base 530. Microstructure 520 canbe used as a mold to fabricate holes for use in, for example, a nozzle.

In other cases, such as that shown in FIG. 6, the microstructuredpattern 610 of film 600 may contain a plurality of microstructures 604that are elongated. For example, as shown in FIG. 6, the microstructuresmay be prisms that are elongated along the length of the film L. In sucha case once the tops of the microstructures are ground, the openingcorresponding to the hole outlet may in fact be an elongated slit, suchas where the tops of the elongated prism is removed along dashed line606.

The microstructures of the current description may be understood ashaving a “diameter” of their opening at different heights of themicrostructure. The diameter may be understood as the maximum distancebetween the edges of the microstructure at a common height. In someembodiments the hole entry may have a diameter of less than 300 microns,or of less than 200 microns, or of less than or equal to 160 microns, orof less than 140 microns. In some embodiments the hole exit may have adiameter of less than 300 microns, or less than 200 microns, or lessthan 100 microns, or less than or equal to 40 microns, or less than 25microns. As shown in the Figures, the microstructures disclosed hereinthat serve as nozzles may be monolithic structures. In other words, themicrostructures that form the actual nozzles are created from, andultimately form a common, single piece of material. This may beunderstood as different from nozzles that are formed through acombination of a number of different parts, where such parts arepotentially made up of different materials. In this regard, as shown inthe above-mentioned figures, the nozzles disclosed herein may bemonolithic structures.

In some cases, a microstructure can be intentionally deformed (i.e.,bent, twisted etc.). Such deformation can be used to affect the flow offluids thorough the nozzles made using these microstructures. Morespecifically, by deforming the microstructures, the resulting nozzlesmay direct the flow of fluids in a desired direction or may lead to adesired angular/volumetric distribution of the fluids in the combustionchamber. Such deformation of the microstructures may be accomplished bythermal means, mechanical means or thermomechanical means. For example,the microstructured first material may be heated to soften andpotentially even partially melt the microstructures causing them todeform under the influence of gravity or other mechanical forces. Inanother embodiment, the microstructures are physically bent by theaction of a mechanical force on them at an angle. Some examples ofpotential applications of mechanical force include squeezing themicrostructures between the mandrels of a vice or forcing them through agap narrower than the height of the microstructures. In yet anotherembodiment, microstructures in the form of microposts may be contactedby a force applied along a plane orthogonal to the height of thestructures, where the force acts downward (in the direction of theheight of the microstructures. This force applied along the tops of themicrostructures may be applied with a hot object at a temperature abovethe melting point of the first material, resulting in the melting thetips of the microposts and forming mushroom shaped microstructures. Whenthe nozzles are made from the mushroom shaped microstructures by themethod of the invention, the tops of the mushroom shaped microstructureslead to large cavities at the inlet side of the resulting nozzles. Suchcavities may act as occlude chambers in a nozzle application.

In yet another embodiment, arrays of microstructures may be deformed.All or some of the individual microstructures in an array may bedeformed. In some cases some of the microstructures are deformed in onepattern while others are deformed in a second pattern. It is possible tohave each individual microstructure within the array be deformed in apredetermined relation to the neighboring microstructures.

EXAMPLES

Objectives and advantages of this invention are further illustrated bythe following examples, but the particular materials and amounts thereofrecited in these examples, as well as other conditions and details,should not be construed to unduly limit this invention. These examplesare merely for illustrative purposes only and are not meant to belimiting on the scope of the appended claims. Unless otherwise noted,all chemicals were obtained from, or are available from chemicalsuppliers such as Sigma-Aldrich Chemical Company, St. Louis. Mo.

Example 1

A microstructured film was prepared by following the general methoddescribed in U.S. Pat. No. 5,845,375 (Miller et. al.). Anethylene-propylene copolymer (available from Dow Chemical Co. [Midland,Mich.] under the trade designation “C700-35N”) resin was melted in a 45millimeters twin screw extruder at a temperature of 230° C. and theextruded melt was passed through a die to form a film. The resultingfilm, being about 0.15 millimeters in thickness, and having a basisweight of 120 g/m⁻², was pressed against a microstructured tooling byfeeding it through a pair of rollers. The microstructured tooling wasmounted onto one of the rollers and chilled to about 90-120° C.(194-248° F.). The roller with the microstructured tooling was rotatedat a surface speed of 0.33 m/s. The microstructure on the surface of thetooling comprised cavities (i.e., prismatic holes) of approximately 120micrometer sides and 370 micrometer deep. The vacancies were arranged ina linear pattern along the x and y direction on the surface of thetooling approximately 520 micrometer apart. When the extruded film waspressed against the microstructured tooling by the action of the secondroller, the pattern of microstructures was replicated in the extrudedpolypropylene film. The resulting polypropylene film (i.e. the replica)exiting the pair of rollers had posts (corresponding to the cavities onthe surface of microstructured tooling) projecting from the filmsurface. The resulting microstructured film contained posts ofapproximately 120 micrometer sides and 370 micrometer depth. Thevacancies were arranged in a linear pattern along the x and y directionon the surface of the tooling approximately 520 micrometer apart

Next, the microstructured film was electroplated with Ni following thegeneral electroplating processes well known in the art. A generaldescription of the electroplating art can be found, for example, in“Modern Electroplating”, Fourth Edition, 2002, John Wiley & Sons,editors: Mordechav Schlesinger and Milan Paunovic. A circular (about 3millimeter in diameter) section of the microstructured film producedabove was cut out and was adhered on a stainless steel disc with the aidof a double stick tape. The surface of the film was made conductive bydepositing a thin Ag film (seed layer) on the microstructured filmreplicas by e-beam evaporation. The process of depositing thin layer ofAg is referred to as silver mirror reaction in the electroplating art.Nickel was electrodeposited on the Ag coated surface of themicrostructured film to replicate the microstructures. Nickelelectrodeposition was carried out in a nickel sulfamate bath at a pHrange of 3.5-4.5 at a temperature of 54.5° C. The solution contained a0.2% of sodium dodecyl sulfate surfactant. Nickel electrodeposition wascarried out in four stages. In the first stage, which lastedapproximately 6 hours, the current density was approximately 27Amperes/m². The second stage lasted 4 hours and featured a currentdensity of 54 Amperes/m², and the third stage lasted 4 hours andfeatured a current density of 108 Amperes/m². The fourth stage was 34hours at a current density of 216 Amperes/m². Nickel electrodepositingwas completed when the thickness of nickel reached about 500micrometers.

After the electrodeposition was completed, the resulting nickel replicawith the microstructured film still in place was planarized andfine-polished to remove enough material so that the holes in the nickelreplica were open and free of burrs. This was accomplished by firstattaching the Ni-plated microstructured film using a wax on a grindingfixture (with the microstructured film down) of a grinder/polisher(available from Ultra Tec Manufacturing, Inc. [Santa Ana, Calif.]).Extreme care was taken to ensure that the Ni-plated microstructured filmwas positioned parallel to the surface of grinding fixture. The fixturewas mounted on the polisher and then the Ni-plated microstructured filmwas planarized and ground using 100, 150, and 220 grit size abrasivefilms, sequentially. The grinding continued until a sufficient amount ofNi was removed, exposing the tops of posts of the microstructuredpolymer. The level of grinding to be done was determined based on thedesired opening size of the resulting nozzle. The Ni-platedmicrostructured film was then polished sequentially using 9, 6, and 3micrometer diamond lapping films. Finally the microstructured film wasseparated from the polished (nickel) nozzle. The nozzle had square sidedholes with approximately 120 micrometer sides. The nozzle holes werearranged in a linear pattern along the x and y direction on the surfaceof the tooling approximately 520 micrometer apart. A backlitphotomicrograph of the nickel fuel injector nozzle of Example 1 inprovided in FIG. 7.

Example 2

Example 2 was prepared in generally the same manner as Example 1. ForExample 2, a low density polyethylene (LDPE) film was provided (about580 micrometers in thickness, prepared from TENITE 18 DOA (obtained fromEastman Chemical Company [Kingsport, Tenn.] under trade designation“TENITE 18”), with 0.5% surfactant TRITON X100 (obtained from DowChemical Company [Midland, Mich.] under trade designation “TRITON X100”)and minor quantities of TiO₂ pigment to make the film white inappearance. The general methods of making structured surfaces, and inparticular microstructured surfaces, on a polymeric layer such as apolymeric film are disclosed in U.S. Pat. Nos. 5,069,403 and 5,133,516,both to Marentic et al., the relevant portions of which are herebyincorporated by reference. U.S. Pat. No. 5,514,120 to Johnston et al.describes how the tooling was created to microreplicate the V shapedfilm described herein. The microstructures on the surface of the toolingincluded linear, V-shaped groves running parallel to one another. TheV-shaped groves had a height of 460 micrometers and 410 micrometerpitch. When the extruded film was pressed against the microstructuredtooling by the action of the second roller, the microstructure wasreplicated in the extruded film. The resulting LDPE microstructured film(i.e. the replica) exiting the pair of rollers had V-shaped groves ofsame size as the microstructured tooling

Next, the resulting microstructured film was electroplated with Ni,planarized and polished using the same process described above forExample 1.

The nozzle of Example 2 had rectangular openings. A backlitphotomicrograph of the nickel fuel injector nozzle of Example 2 isprovided in FIG. 8.

Example 3

In this example, hollow micro-needle arrays made of polycarbonate wereused as the microstructured first material. The micro-needle arrays wereprepared using the general processes described in commonly owned andassigned US Patent Publication No. US2009/009537 (DeVoe, et. al.). Eacharray had 18 micro-needles that were 900 micrometers tall and a taperedcone with a large, fixed end that was approximately 270 micrometers indiameter. The micro-needles were similar in shape to those shown in FIG.10 of US Patent Publication No. US2009/009537 (DeVoe, et. al.). Theconical shape made it easy to bend the needles near the top. The goalwas to deform all of the micro-needle tips by bending them so that they“pointed” in an off-axis direction. The total height of the substrateplus the micro-needles was approximately 2.52 millimeter (0.099 inch). Agap between the smooth jaws of a miniature tooling vise was set to about2.159 millimeters (0.085 inches). Once the gap was set, thepolycarbonate micro-needle array was pressed by hand through the gap.All of the needles in the array were bent by a similar amount. FIG. 9 isa photomicrograph of the deformed micro-needle arrays illustrates theresults of bending the micron-needles over. While in this Example 3, thevise jaws were set parallel to each other; they did not need to beparallel. A non-parallel gap in the cross-web direction would result inthe needles on one side of the substrate being bent more than theneedles on the other.

The deformed microneedle pre-form was then silver sputtered, nickelelectro-plated and backside ground using exactly the same processes usedin Example 1 above.

Example 4

Example 4 was prepared in generally the same manner as Example 3, exceptthat the micro-needle arrays were deformed by pressing an aluminumcylindrical rod on the center of the micro-needle array. The deformedmicro-needles were bent at their tips so as to point outward from thecenter of the array in a circular arrangement.

The deformed microneedle pre-form was then silver sputtered, nickelelectro-plated and backside ground using exactly the same processes usedin Example 1 above.

1. A method of fabricating a nozzle comprising the steps of: forming afirst microstructured pattern in a first material, the firstmicrostructured pattern comprising a plurality of discretemicrostructures; deforming at least one of the plurality of discretemicrostructures, resulting in at least one deformed discretemicrostructure; replicating the first microstructured pattern in asecond material different than the first material to make a replicatedstructure; processing the replicated structure into a nozzle having aplurality of through-holes in the second material and corresponding tothe plurality of microstructures in the first microstructured pattern,said processing comprising removing the first material from thereplicated structure.
 2. The method of claim 1 wherein said formingcomprises casting and curing the first material.
 3. The method of claim1 wherein said forming comprises extruding the first material.
 4. Themethod of claim 1, wherein the first material comprises a polymer andthe second material comprises a metal.
 5. The method of claim 1, whereinsaid processing further comprises removing enough of the second materialof the replicated structure to expose tops of the microstructures in theplurality of microstructures in the first microstructured pattern. 6.The method of claim 5, wherein said removing comprises planarizing thesecond material.
 7. The method of claim 1, wherein the second materialcomprises an electroplating material, and said replicating compriseselectroforming the second material so as to cover over the firstmicrostructured pattern.
 8. The method of claim 7, wherein saidprocessing further comprises removing enough of the second material fromthe replicated structure to expose tops of the microstructures in theplurality of microstructures in the first microstructured pattern. 9.The method of claim 1, wherein the second material comprises a ceramic.10. The method of claim 1, wherein the plurality of discretemicrostructures comprises a discrete microstructure that is at least aportion of a three-dimensional rectilinear body.
 11. The method of claim10, wherein the three-dimensional rectilinear body is an elongatedprismatic structure.
 12. The method of claim 1, wherein the plurality ofdiscrete microstructures comprises a discrete microstructure that is atleast a portion of a three-dimensional curvilinear body.
 13. The methodof claim 1, wherein said deforming comprises deforming an array of theplurality of discrete microstructures, resulting in an array of deformeddiscrete microstructures.
 14. The method of claim 1, wherein saiddeforming comprises bending or twisting, resulting in at least one bentor twisted discrete microstructure.
 15. The method of claim 1, whereinsaid deforming occurs by mechanical, thermal or thermomechanical means.16. The method of claim 1, wherein the plurality of discretemicrostructures of the first pattern comprise re-closeable fastenerswith posts or mushroom-shaped tops.